1. Field of the Invention
The present invention relates to a DC cooling system and more particularly to a simple, reliable, compact and power efficient DC cooling system for use in and with electronic equipment enclosures.
2. Description of the Related Art
Electronic equipment enclosures are frequently located out-of-doors where they are exposed to ambient temperatures. Typically, enclosures have at least one chamber in which heat generating electronic components are situated. At certain levels heat may degrade the operation of the components whereas lowering temperature may improve performance. Often a cooling system is operatively connected to the enclosure to ensure that the temperature in the electronic component chamber is maintained within a safe and effective range. Cooling systems include heat exchangers for above ambient cooling and air conditioners for below ambient cooling, as well as other devices and variations or combinations of the above. The more powerful cooling systems include a compressor, a condenser, an expansion device and an evaporator. Usually, such a system is reliable and provides the necessary cooling, although too much power may be consumed. When working in a direct current (xe2x80x9cDCxe2x80x9d) backup mode, where power is provided by batteries, the amount of power consumed is a very important issue and minimization of power consumption is an imperative.
Further, a situation may arise where the ambient temperature is so low that refrigerant in the compressor is cooled sufficiently to change phase from gas to liquid. When this occurs, the compressor may not start, or the compressor may damage itself so that the cooling system becomes inoperative. High powered heaters may be used to heat the compressor and its contents, to keep the compressor lubricated and to keep refrigerant from becoming liquid, but these heaters are expensive and they require excessive energy to operate.
What is described here is a cooling system for an electronic equipment enclosure and an enclosure having such a system, where the enclosure includes a components chamber where heat is generated, a housing operatively connected to the components chamber for enclosing elements of the cooling system, the cooling system including a compressor, a condenser, an evaporator, a refrigerant and means for expanding the refrigerant, and a conduit formed around the compressor and extending into the components chamber of the enclosure, a fluid for selectively moving in the conduit to transport heat from the components chamber to the compressor and a pump for selectively moving the fluid along the conduit. The cooling system is very compact, operable in a DC mode and efficient.
There are a number of advantages, features and objects achieved with the present invention which are believed not to be available in earlier related devices. For example, one advantage is that the present invention provides a very low cost, reliable and simple apparatus to use heat generated in the equipment enclosure to heat a compressor during cold ambient conditions. The present invention obviates the need for an expensive, high powered compressor heater. Another feature of the present invention is to provide a cooling system which is more efficient because the system is compact and effectively designed and the system uses the heat generated by the same components which are to be cooled in a situation where the ambient temperature adversely affects the compressor of the cooling system. The present invention also offers back-up capabilities should the compressor fail. Another advantage of the present invention is that it provides an equipment enclosure that uses less power than prior enclosures having the same heat removal capacity.
Air conditioning systems with independent fluid flow systems have been used in the past but not in the same way as disclosed here. See for example, U.S. Pat. No. 6,205,796 which discloses a refrigeration system for both a cold plate and a heat exchanger as well as an air flow system to control humidity.
A more complete understanding of the present invention and other objects, advantages and features thereof will be gained from a consideration of the following description of the preferred embodiment read in conjunction with the accompanying drawing provided herein.